THE IMPORTANCE OF TIME DOMAIN RESPONSE MUST READ


Speaker designers ignore or downplay the importance of TIME. Why?

A high end speaker should be as accurate as possible and that means it should not only be optimized with regard to frequency response but time response.

Back in the 70’s and around that time, speaker engineers thought that a perfect speaker would be one that had a flat response. This idea has waxed and waned in popularity over the years and even now there is no consensus.

What the speaker engineers forgot to consider is Time response.

The time reponse of a speaker is how fast it starts and stops. A perfect speaker would have a perfect time response of 0. Since this is not possible, we must get as close to it as possible. The problem is speakers engineers have neglected this aspect of the design and so speakers over the last 40 years have not improved in this respect.

Time is such an important aspect of the sound we hear. We not only hear tone but also time. The brain can detect time differences of only a few microseconds. Experiments have shown that the start of each note is what we use to determine what instrument is producing that sound.

We must ensure that our crossovers do not smear the time response because it will be heard by our ears. Time inaccuracy is why high end speakers do not sound like real instruments.

Diffraction from the cabinet can also cause time smear. We need spherical cabinets not square boxes. Tweeters need to be time aligned in order to ensure that when the woofer stops so does the tweeter. When the woofer starts, so must the tweeter. The woofer itself has to have a Qts of ZERO to prevent time smear. Ports must not be used or else you will get ringing.

We need to make it mandatory for speaker companies to publish the time response of all their speakers so that consumers can easily compare and decide exactly what they want. Some may actually prefer a speaker that has a poorer time response and that is fine. The problem is, we cant decide unless we know what we are buying can we?

Unfortunately, 90% of speakers on the market, even high end speakers have ports. And they are also made of cheap wood, even though there must be better materials by now. Some materials ring more than others.

So dont be deceived folks. If you want better speakers, you will probably have to make them yourself because speaker manufacturers dont care about sound quality. They spend millions of dollars on anechoic chambers all so that they can get a flat response but they spend zero effort on better time domain response. We are being duped.

kenjit

@perkri    

If I'm not mistakebn, there has been a few different patents variations of series crossovers.  I haven't looked in a few years, but I believe Eric Alexander of Tekton filed the last patent variation.... Either way,  yes,  the Acoustic Reality crossover is one of the more simple versions.  

I have built many, many, many crossovers.  I've taken a ton of measurements and can tell you that series crossovers are not necessarily the only way to go.  But if you want to use less parts and are careful with inductance, they are typically very good and on the right drivers can be the best for some designs.  

@erik_squires 

 

Sorry, should have been more clear :) When using the ARSXO, I am struggling to see what purpose a cap would have on the woofer, and how it would be implemented. In a more traditional Cap/Res/Ind series or parallel crossover, sure, use of a cap is not a mystery. Just not in the ARSXO. Would love to see how that is done! Always wanting to learn new stuff…

@timlub 

 

Im a minimalist for sure :) Building a speaker for a friend, that is specifically intended to go into a shelf in a Ikea kallax shelving unit. 335mm cube. Not fun… So, small sealed full range driver and the rest is for a band pass sub. The boxes are doing most of the work, and the drivers were chosen for their suitability in the boxes. Even so, there are six components on the FR driver just to manage it. There are no”crossover” parts per say as the drivers/enclosures are doing the high pass/low pass work. But I digress :) Guess that was to illustrate how I very much prefer fewer parts.

@perkri 

Here's a good blog post explaining the differences.   You can also use a free simulator like XSim to experiment without actually building anything.

 

https://www.tubecad.com/2017/11/blog0402.htm

@erik_squires 

Caps and coils are fundamental to creating high and low pass filters. Here’s a post I wrote a long time ago that may help you, though it covers the more common parallel crossovers:

Thanks for those links, I've sometimes wondered how that stuff works :-)